French presidential candidate Emmanuel Macron spoke with former U.S. president Barack Obama on the phone on Thursday, in an apparent sign of support just three days before the first round of an uncertain presidential election.

Macron said Obama wanted to exchange views about the French presidential campaign and that the ex-president had stressed how important the relationship between the two countries was.

"Emmanuel Macron warmly thanked Barack Obama for his friendly call," Macron's party "En Marche!" said in a statement.

In a separate statement, Obama's spokesman added: "an endorsement was not the purpose of the call, as President Obama is not making any formal endorsement in advance of the run-off."

Macron is the only candidate so far to have said he has talked with Obama, a popular figure in France.

Macron, a pro-EU centrist, is leading most opinion polls for the election's first round and is expected to contest a second-round run-off with far-right leader Marine Le Pen.